1. Field of the Invention
The present invention relates to semiconductor nanostructures and their producing method and applications.
2. Description of Related Art
Silicon nanostructures have potential applications in optoelectronics. For example, they can function as light-absorbing layer, light-emitting layer, or anti-reflection layer of the optoelectronics. Epitaxy, Silicon On Insulator (SOI), vapor-liquid-solid growth, and chemical etching methods may be used to produce the silicon nanostructures.
In these methods, epitaxy and Silicon On Insulator methods are disadvantageous as their high manufacturing cost. Vapor-liquid-solid growth method is subject to high temperature and high vacuum conditions and the life cycle of the carriers is reduced due to metal contamination. Chemical etching method suffers from the complicated processes and high manufacturing cost, because the silicon nanostructures are produced from an epitaxial growth thin film, which is formed by costly chemical vapor deposition and laser annealing method.
In another aspect, silicon nanostructures are typically formed on silicon substrate to avoid lattice dis-match problems. In some applications such as solar cells, photo detectors, and biosensors, however, one-tenth of the thickness of the silicon substrate may be enough, and even only the nanostructures are needed. In the later case, prior art utilizes wet etching method to etch the silicon substrate for obtaining a required thickness. Most of the silicon substrate will be etched and wasted. The manufacturing cost of optoelectronics will be therefore increased.
In another aspect, technology of transferring silicon nanostructures or silicon microstructures to a hetero-substrate also has potential applications. Typically prior art utilizes epitaxy or Silicon On Insulator method to form silicon nanostructures on a silicon substrate. The silicon substrate is then selectively etched and the remained silicon nanostructures are transferred to another substrate, such as a glass substrate or a plastic substrate. As mentioned above, both the epitaxy and Silicon On Insulator method are cost-plus methods.
Accordingly, it would be advantageous to provide silicon nanostructures and their forming methods and applications for decreasing the manufacturing cost, increasing the yield, and promoting the performance of the nanostructures.